1. Field of the Invention
The present invention relates to an optical disk and an optical disk apparatus for readily acquiring information about the disk itself such as a track pitch, a recording linear velocity and a recording angular velocity of the loaded optical disk during recording or reproduction.
2. Description of the Related Art
During recording or reproduction of disks with a constant recording linear velocity, it is beneficial to acquire beforehand the target recording linear velocity of an optical disk to be used. When the disk stops at a certain position in the radial direction and then restarts rotating, it is possible to accurately set an adequate rotational speed of the disk for providing the target recording linear velocity, if the same is acquired previously. The target recording linear velocity can be reached in a short time. If there are previously acquired both of the track pitch and the recording linear velocity, it is possible to accurately set a track jump target distance (or a target feed amount of an optical pickup) toward a destination address to be accessed, and an adequate rotational speed of the disk for providing the target recording linear velocity at the access destination. This enables an access to the target position in a short time and to promptly start recording or reproduction.
Likewise, during recording or reproduction of disks with a constant recording angular velocity, it is also beneficial to acquire beforehand the target recording angular velocity of an optical disk to be used. When the disk stops and then starts rotating, the target recording angular velocity can be resumed in a short time. If there are previously acquired both of the track pitch and the recording angular velocity of an optical disk to be used, it is possible to accurately set a track jump target distance (or a target feed amount of an optical pickup) toward a destination address to be accessed. This enables an access to the target position in a short time and to promptly start recording or reproduction.
There is a case of adjusting the time axis correction amount for a recording signal or the laser beam's recording power according to the recording linear velocity. The recording linear velocity must be previously recognized to set the time axis correction amount.
A flowchart in FIG. 2 is used to exemplify a procedure for acquiring information about a track pitch and a recording linear velocity when an optical disk of a constant recording linear velocity mode is loaded on a conventional optical disk apparatus (e.g., CD-R/RW drive apparatus). When the optical disk is loaded (S1), a disk type (CD-ROM, CD-R, CD-RW, etc.) is detected (S2) and the TOC (Table of Contents) information is acquired (S3). Then, an optical pickup is moved to a position within a radius of 25 mm, i.e., a start position of a program region (S4). At this position, a spindle motor is controlled to acquire a specified wobble frequency or RF frequency. The spindle motor's rotation number is measured at that time (S5). Based on this measurement result, the recording linear velocity is computed (S6). Thereafter, the optical pickup moves to a position within a radius of 40 mm, i.e., a middle of the program region (S7). The time information at that position is acquired (S8). The track pitch is computed based on that time information and the previously acquired recording linear velocity (S9). Thus, the information about the track pitch and the recording linear velocity has been acquired (S10).
The conventional optical disk apparatus spends a lot of time for preparing for recording or reproduction because loading the optical disk necessitates complicated processing as shown in FIG. 2.